Undefined hidden symbol compiling code with generics and const reference to static

[davidzeng0]

I tried this code:

fn test<T>()
where
	T: Trait
{
	let pointer = T::STRUCT;
}

#[repr(C)]
#[derive(Debug)]
struct Struct {
	function: fn()
}

static STRUCT: Struct = Struct { function: test::<()>  };

trait Trait {
	const STRUCT: &'static Struct;
}

impl Trait for () {
	const STRUCT: &'static Struct = &STRUCT;
}

fn main() {
    println!("{:?}", <() as Trait>::STRUCT);
}

I expected to see this happen: prints

Struct { function: 0x<addr> }

Instead, this happened:

error: linking with `cc` failed: exit status: 1
  |
  = note:  "cc" "-m64" "/tmp/rustcc6uHbt/symbols.o" "<10 object files omitted>" "-Wl,--as-needed" "-Wl,-Bstatic" "<sysroot>/lib/rustlib/x86_64-unknown-linux-gnu/lib/{libstd-*,libpanic_unwind-*,libobject-*,libmemchr-*,libaddr2line-*,libgimli-*,librustc_demangle-*,libstd_detect-*,libhashbrown-*,librustc_std_workspace_alloc-*,libminiz_oxide-*,libadler2-*,libunwind-*,libcfg_if-*,liblibc-*,liballoc-*,librustc_std_workspace_core-*,libcore-*,libcompiler_builtins-*}.rlib" "-Wl,-Bdynamic" "-lgcc_s" "-lutil" "-lrt" "-lpthread" "-lm" "-ldl" "-lc" "-L" "/tmp/rustcc6uHbt/raw-dylibs" "-B<sysroot>/lib/rustlib/x86_64-unknown-linux-gnu/bin/gcc-ld" "-fuse-ld=lld" "-Wl,-znostart-stop-gc" "-Wl,--eh-frame-hdr" "-Wl,-z,noexecstack" "-L" "<sysroot>/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-o" "/crate/root/test2/target/debug/deps/test2-4da9f5e7d055ae9a" "-Wl,--gc-sections" "-pie" "-Wl,-z,relro,-z,now" "-nodefaultlibs"
  = note: some arguments are omitted. use `--verbose` to show all linker arguments
  = note: rust-lld: error: undefined hidden symbol: test2::STRUCT::h113f20394fd71d07
          >>> referenced by main.rs:5 (src/main.rs:5)
          >>>               /crate/root/test2/target/debug/deps/test2-4da9f5e7d055ae9a.973g56r0h88wi65qwm2rwg85k.rcgu.o:(test2::test::h45a33cc559ef8b90)
          collect2: error: ld returned 1 exit status

Meta

rustc --version --verbose:

rustc 1.87.0-nightly (f8c27dfe1 2025-03-24)
binary: rustc
commit-hash: f8c27dfe1a2e7fb538fd91dad53de06992c7c967
commit-date: 2025-03-24
host: x86_64-unknown-linux-gnu
release: 1.87.0-nightly
LLVM version: 20.1.1

With help from others, I have confirmed this bug is also reproduced on windows, on both the stable and nightly compilers. The code compiles fine on playground, godbolt, and miri, but not with cargo build.

[tmiasko]

It appears that mono item collector omits references from var debug info.